This grant will provide a "state of the art" transmission electron microscope to be equipped with STEM and microprobe for research in membrane-cytoskeletal interrelationships by a core group of cell biologists and other users. Questions posed in the research include: 1) function and assembly of specialized intramembrane particles during secretion, utilizing high resolution freeze-fracture electron microscopy and mutant analysis; 2) structure and function of cilia, including the transmission electron microscopy of sliding microtubules and dynein arm morphology; 3) calcium localization by morphological techniques including electron microscopy during stimulus-secretion coupling, ciliary arrest and actin mobilization in tissue culture cells; 4) the mechanism of translocation of particles on ciliary membranes of Chlamydomonas; and 5) transmembrane structure and linkage during capping in model systems and WiL 2 lymphocytes.